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Timing Measurement. Authors:. Date: 2008-07-16. Abstract. This submission summarizes the Timing Measurement feature in 802.11v in general and specifically addresses two LB133 comments on Timing Measurement (268, 1280).
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Timing Measurement Authors: Date: 2008-07-16 Ganesh Venkatesan, Intel Corporation
Abstract This submission summarizes the Timing Measurement feature in 802.11v in general and specifically addresses two LB133 comments on Timing Measurement (268, 1280). Note: There are more LB133 comments on Timing Measurement that are not directly addressed by this submission and will be addressed later. Ganesh Venkatesan, Intel Corporation
Timing Measurement motivations Use the measurement data in a higher layer algorithm to: • Synchronize clocks between two STAs or synchronize systems to a common clock • Non-AP STA-based determination of location Researching the motivations further demonstrated that accuracy requirements on the time measurement data are too tight (resulting in complex implementation(s)) in order to determine location. Hence the ‘non-AP STA-based location determination’ goal is now dropped. Ganesh Venkatesan, Intel Corporation
Timing Measurement Support Ganesh Venkatesan, Intel Corporation
Timing Measurement Frame Ganesh Venkatesan, Intel Corporation
Frame Exchanges to Get the Required Data Ganesh Venkatesan, Intel Corporation
Timestamps • Time of Departure • Time of Arrival (discussed in this submission) Ganesh Venkatesan, Intel Corporation
Receive PLCP (example Clause 15 PHY) Ganesh Venkatesan, Intel Corporation
What happens in the PLCP? If the MIB variable dot11MgmtOptionTimingMsmt exists and is set to TRUE, the PLCP shall do the following: • Save the value of the Timestamp counter corresponding to the time when the first PMD_DATA.Indication for the incoming frame was received from the PMD, ta, • Estimate timestamp offset between when the first PMD_DATA.Indication occurred and when the PCLP header will be fully received and determined to be valid, toffset, • Save the value of the Timestamp counter corresponding to the actual time when the PCLP header is received and determined to be valid, tactual • Determine timestamp error = tactual – (ta + toffset), and • Forward tactual, timestamp error values within RXVECTOR Ganesh Venkatesan, Intel Corporation